The present invention generally relates to a liquid-cooled four-valve cylinder head for a multi-cylinder internal-combustion engine and more particularly to a cylinder head construction which is structurally rigid and easy to produce.
A cylinder head of the general type concerned here is disclosed in German Patent Specification No. 3,513,126. In order to stiffen the cylinder-head housing, in the region of the longitudinal mid-plane of the cylinder head, there are longitudinal ribs which are connected to transverse booms between combustion-space portions. At the same time, to reinforce the bottom portions on the same side as the combustion space, the transverse booms are continued by supporting columns in the water space as far as the cylinder-head bottom. Furthermore, the guide housings formed on the lateral housing walls and intended for cup tappets are connected both to the transverse booms and to the longitudinal ribs, thereby achieving a reinforcement of the cylinder-head regions located between the transverse booms, including the centrally arranged spark plug. This cylinder-head construction is especially suitable for producing cylinder heads with roof-shaped combustion spaces and with the associated large valve angles.
It is an object of the present invention to provide a cylinder head construction which guarantees the best possible rigidity in a simple way, even when the combustion space is of relatively shallow design.
These and other objects of the present invention are achieved by a unique combination and arrangement of elements of the cylinder-head.
According to certain preferred embodiments of the present invention it is possible to obtain a cylinder-head construction which has a shallow combustion-space limitation in the cylinder-head bottom and which possesses the best possible rigidity and is therefore especially suitable for use in Diesel engines with four valves per cylinder.
A further advantage of the certain preferred embodiments of the present invention is that the high rigidity of the cylinder-head housing is mainly achieved merely by an appropriate constructional combination of the components provided in the cylinder-head for engine operation such as, for example, the guide housings for the cup tappets or the valve channels. As a result, not only is the cylinder-head according to preferred embodiments the invention simpler to produce in casting terms, but weight is also saved because of the omission of special reinforcing ribs.
The guide housings perform the function of stiffening the cylinder-head housing in the longitudinal direction. At the same time, this results in an arrangement of the valves with a small valve angle which is crucial for the shallow design of the combustion-space portions of the cylinder-head bottom.
Because chamber channels and valve channels are combined, it is not possible to flush the hot chamber portion in the cooling-fluid space. In order nevertheless to ensure a good cooling of this chamber portion, the cooling water is guided in a controlled way round the valve channels through flow-guide channels within the cooling-fluid space.
At the same time, cooling is further intensified because cooling water at a relatively low temperature is additionally sprayed directly into the housing indentations between the valve channels. The cooling water reaches parts of the chamber wall directly via the housing indentations, thus achieving a cooling effect similar to a flushing of the chamber.
Additionally, further features of preferred embodiments of the present invention ensure a favorable distribution of the clamping forces introduced into the cylinder-head bottom by the clamping screws via the hollow struts and of the gas forces acting on the bottom portion located on the same side as the combustion space.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.